diff --git a/spring-mvc/servlet/src/main/java/com/example/servlet/domain/member/Member.java b/spring-mvc/servlet/src/main/java/com/example/servlet/domain/member/Member.java
new file mode 100644
index 00000000..a9a426a2
--- /dev/null
+++ b/spring-mvc/servlet/src/main/java/com/example/servlet/domain/member/Member.java
@@ -0,0 +1,20 @@
+package com.example.servlet.domain.member;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter @Setter
+public class Member {
+
+    private Long id;
+    private String username;
+    private int age;
+
+    public Member() {
+    }
+
+    public Member(String username, int age) {
+        this.username = username;
+        this.age = age;
+    }
+}
diff --git a/spring-mvc/servlet/src/main/java/com/example/servlet/domain/member/MemberRepository.java b/spring-mvc/servlet/src/main/java/com/example/servlet/domain/member/MemberRepository.java
new file mode 100644
index 00000000..3f13039a
--- /dev/null
+++ b/spring-mvc/servlet/src/main/java/com/example/servlet/domain/member/MemberRepository.java
@@ -0,0 +1,40 @@
+package com.example.servlet.domain.member;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class MemberRepository {
+    // 동시성 문제 -> ConcurrentHashMap, AtomicLong 사용
+    private static Map<Long, Member> store = new HashMap<>();
+    private static long sequence = 0L;
+
+    // singleton
+    private static final MemberRepository instance = new MemberRepository();
+
+    public static MemberRepository getInstance() {
+        return instance;
+    }
+
+    private MemberRepository() {
+    }
+
+    public Member save(Member member) {
+        member.setId(++sequence);
+        store.put(member.getId(), member);
+        return member;
+    }
+
+    public Member findById(Long id) {
+        return store.get(id);
+    }
+
+    public List<Member> findAll() {
+        return new ArrayList<>(store.values());
+    }
+
+    public void clearStore() {
+        store.clear();
+    }
+}
diff --git a/spring-mvc/servlet/src/test/java/com/example/servlet/domain/member/MemberRepositoryTest.java b/spring-mvc/servlet/src/test/java/com/example/servlet/domain/member/MemberRepositoryTest.java
new file mode 100644
index 00000000..75ea58de
--- /dev/null
+++ b/spring-mvc/servlet/src/test/java/com/example/servlet/domain/member/MemberRepositoryTest.java
@@ -0,0 +1,47 @@
+package com.example.servlet.domain.member;
+
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+class MemberRepositoryTest {
+
+    MemberRepository memberRepository = MemberRepository.getInstance();
+
+    @AfterEach
+    void afterEach() {
+        memberRepository.clearStore();
+    }
+
+    @Test
+    void save() throws Exception {
+        // given
+        Member member = new Member("hello", 20);
+
+        // when
+        Member savedMember = memberRepository.save(member);
+
+        // then
+        Member findMember = memberRepository.findById(savedMember.getId());
+        Assertions.assertThat(findMember).isEqualTo(savedMember);
+    }
+
+    @Test
+    void findAll() throws Exception {
+        // given
+        Member member1 = new Member("member1", 20);
+        Member member2 = new Member("member2", 30);
+
+        memberRepository.save(member1);
+        memberRepository.save(member2);
+
+        // when
+        List<Member> result = memberRepository.findAll();
+
+        // then
+        Assertions.assertThat(result.size()).isEqualTo(2);
+        Assertions.assertThat(result).contains(member1, member2);
+    }
+}
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